Disposable laminar fabric comprising paper bonded to a polyolefin reinforcing netting

ABSTRACT

A DISPOSABLE FABRIC COMPRISING PAPER BONDED TO A PLASTIC REINFORCING WEB WHICH IS INTEGRALLY EXTRUDED AND HAS ELONGATION CHARACTERISTICS SIMILAR TO THOSE OF THE PAPER.

INVENTOR DANIEL H. FRANK BY HM Mm+ 5 I: z :I 12:

ATTORNEYS.

g- 17, 1971 D. H. FRANK DISPOSABLE LAMINAR FABRIC COMPRISING PAPER BONDED TO A POLYOLEFIN REINFORCING NETTING Filed March 12, 1969 United States Patent 3,600,262 DISPOSABLE LAMINAR FABRIC COMPRISING PAPER BONDED TO A POLYOLEFIN REIN- FORCING NETTING Daniel H. Frank, Port Washington, N.Y., assignor to Disposables, Inc., Whitestone, N.Y. Filed Mar. 12, 1969, Ser. No. 806,480 Int. Cl. 1832b 27/10 U.S. Cl. 161-79 3 Claims ABSTRACT OF THE DISCLOSURE A disposable fabric comprising paper bonded to a plastic reinforcing web which is integrally extruded and has elongation characteristics similar to those of the paper.

FIELD OF THE INVENTION The invention concerns fabrics so inexpensive that they may be discarded after use, particularly the kind which comprises paper bonded to a synthetic reinforcing web.

THE PRIOR ART At the present time disposable fabrics are widely used in application where the dilficulty or expense of cleaning conventional fabrics makes it more preferable to use an item for a short time and then discard it entirely. Such fabrics are particularly well adapted for sanitary applications, for various types of work clothes, and for medical applications where there is a requirement of sterility. Lately, in addition, such fabrics have even been used in items of ordinary apparel, particularly in the field of feminine fashion where they make it less costly for women to renew their Wardrobes.

In order to be economical, disposable fabrics are normally made of one of a variety of inexpensive paper materials, which provides the body, opacity, texture and absorbency associated with fabrics of the conventional cloth variety. However, in substituting paper for cloth certain disadvantages are incurred, among which is the fact that paper has a much lower tensile strength than is desirable in a fabric.

This problem has been partially solved by the use of a cross-laid nylon reinforcing web which is bonded between two paper layers. The nylon used is a high tensile strength material which lends a degree of strength to the composite fabric in which it is included.

But this solution has not been entirely satisfactory. It appears to me that the reason for this is that, inasmuch as the tensile strength of the nylon reforcing web material is so great, and its elongation per unit of tensile stress is so relatively high, when a composite fabric of paper and high strength nylon webbing is subjected to tensile stress the paper will elongate markedly less than will the nylon reinforcing web. Consequently, the paper stretches to the point of rupture before a considerable proportion of the tensile strength of the reinforcing web has been made available to the paper. Once the paper ruptures, the integrity of the fabric has been elfectively violated. Thus, it is the paper that gives the fabric its body, opacity, texture, absorbency and other cloth-like characteristics, so that as soon as the paper is ruptured, the fabric for all practical purposes has a hole in it and is no longer useful. While the nylon webbing generally remains undamaged at the site of the hole, it is nonetheless merely a transparent network of widely spaced threads having none of the required cloth-like characteristics.

Thus, it is my belief that such a high strength reinforcing web is mismatched to the paper, so that much of its strength is wasted. To state the matter another way, the

3,600,252 Patented Aug. 17, 1971 "ice tensile strength of the webbing is but poorly transferred to the paper, and the popular axiom that a chain is only as strong as its weakest link-the paperis applicable.

In addition, the use of a high strength nylon reinforcing web is uneconomical. The reinforcing web is one of the principal items of cost in the manufacture of disposable fabrics of this nature, and it is my belief that this cost has been expended for excess strength which does not contribute to the end product.

Another disadvantage of employing a high strength nylon web is that the cross-laying process by which the webbing is manufactured leaves it with considerable residual internal stresses and distortions which afiect the fabric by making it difficult to roll, unroll, lay, cut, sew, or otherwise handle. These internal stresses and distortions also affect the way in which the disposable fabric hangs or drapes when it is manufactured into garments or other end use products, which is particularly objectionable where feminine fashions are concerned.

SUMMARY OF THE INVENTION The present invention provides an improved disposable fabric of the kind comprising paper and a. synthetic web combined in a laminar relationship; particularly a fabric of this kind which withstands relatively greater tensile loads prior to rupture, which is less expensive to manufacture, and which is free of internal stresses and distortions affecting the handling and drape of the fabric.

The invention is carried out by providing a plastic reinforcing web material, the elongation characteristics of which are more nearly matched to those of the paper layers of the laminate. Consequently, the reinforcing material stretches together with the paper when the laminate is subjected to tensile stress, and thus absorbs a. greater portion of the load. As a result, the composite material can withstand a higher level of tensile stress before rupture occurs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one form of apparatus for bonding the paper layers to the synthetic reinforcing web in the manufacture of the disposable fabric of the invention;

FIG. 2 is a similar schematic diagram showing an alternative way of applying adhesive for bonding the paper layers to the synthetic reinforcing web in an apparatus similar to that of FIG. 1;

FIG. 3 is a similar schematic diagram showing another alternative way of applying adhesive; and

FIG. 4 is a similar schematic diagram showing yet another alternative way of applying adhesive.

The same reference characters refer to the same ele ments throughout the several views of the drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminar disposable fabric of this invention may be manufactured by any of the processes which are now conventional in the industry, for example the process depicted in FIG. 1. There it is seen that paper sheets 100, which are intended to form the outer layers of the disposable fabric, are unwound from respective supply reels 102 in the direction of arrows 104, while an intermediate synthetic reinforcing web 106 is simultaneously unwound from a supply reel 108 in the direction indicated by arrows 110.

The outer layers may be composed of tissue, wadding, kraft or any other paper-like material. If desired they may be provided with various coatings, foils or films, and they may be creped or uncreped as required, all in order to impart the desired properties of water repellency, stretch, absorbency, etc., to the finished product.

In accordance with this invention, the intermediate reinforcing web 106 is a net-like material, the composition and filament size of which are specifically selected so that the material 106 approximately matches the elongation characteristics of the paper layers 100 when the composite fabric is subjected to tensile stress.

In order to bond the outer paper layers 100 to the intermediate reinforcing web 106, gluing apparatus 112 is provided for applying liquid adhesive material 114 to the web. In the specific apparatus of FIG. 1, the web 106 is guided by rollers 116 directly into a bath of the adhesive material 114 contained within a tank 118. The adhesive may be any of the conventional adhesives, e.g., latex, dextrose, starch, polyvinyl chloride, polyvinyl acetate, or other conventional inexpensive adhesive in either a water or other base vehicle. Of course, the adhesive should be compatible with the paper layers 100, have a reasonably short drying time, and should wet and adhere to reinforcing web 106.

After the adhesive 114 has been applied to the web, the paper layers 100 are guided into contact with opposite sides of the web by rollers 120, and the three layers 100 and 106 are then squeezed together in continuous fashion between a pair of combining rollers 122. A three-layer laminar fabric 124 emerges from the combining rollers as indicated by arrow 125, and is then passed over heated drying cans 126 which remove the solvent from the adhesive 114 within a short time. Of course, other methods of drying could be employed. For instance, alternative methods of drying (not shown) would be to pass the laminar fabric 124 through a warm air tunnel, or past radiant heaters.

On emerging from the drying apparatus the fabric 124 passes over a guide roller 128 and is wound onto an output roll 130, so as to thereby be ready for conversion into a garment or any other end use product for which the disposable fabric 124 is suitable.

FIG. 2 shows a different from of gluing apparatus 212 in which the reinforcing web 106 is guided by rollers 216 into contact with an adhesive applying roller 217, which in turn picks up the adhesive 114 from a roller 219 partially immersed in the liquid material 114 contained within the tank 118.

In the gluing apparatus 312 of FIG. 3, alternatively, the adhesive material 114 is sprayed on both sides of the reinforcing web 106 as it passes between nozzles 313 which are supplied by pipes 315.

In FIG. 4 there is shown yet another alternative gluing apparatus 412 in which liquid adhesive material 114 is picked up from tank 118 by a partially immersed roller 419 and is transferred by intermediate rollers 421 to an application roller 417 which is formed with surface grooves 423 for trapping the liquid adhesive 114 on the surface of the roller. The application roller 417 cooperates with another roller 425 to grip the reinforcing web 106, and thus transfer adhesive material 114 from the grooves 423 to the web 106.

The viscosity of the adhesive 114 should be such, relative to the pick-up, wicking, and absorbency characteristics of the paper layers 100; and the pressure of the combining rollers 122 should be such as to squeeze out the proper amount of adhesive material 114 from the intermediate net material 106; so that the paper layers 100 bond to each other through the interstices of the net 106. In addition, the strands of the intermediate net material 106 are also bonded to, and encapsulated between, the outer paper layers 100. However, the amount of adhesive 114 which escapes into the interstices of the netting 106 should be small enough to minimize its effect on the softness, drape, hand, absorbency, and other properties of the resulting laminar fabric 124. For example, in a typical fabric employing a 4 x 4 count netting as the web 106, the adhesive material 114 should cover approximately of the total area of the confronting faces of the paper layers 100.

The gist of the present invention is in the reinforcing web 106 being such as to provide appropriate elongation under tensile stress. Typically, under tensile loading the paper material employed for the outer layers will stretch (extend elastically) relatively easily, but will undergo a maximum elongation of only about 10 to 25% before it ruptures. The high strength nylon material previously employed to manufacture reinforcing Webs for such disposable fabrics tends to stretch more for the same tensile loading. Hence much of the nylons strength is unavailable for reinforcing the paper. Consequently the paper reaches its maximum elongation and then ruptures well before the reinforcing web is itself stressed to its maximum tensile loading. Thus, the utility of the disposable fabric is destroyed well before the full strength of the reinforcing web can be brought to bear.

The present invention employs a reinforcing web 106 generally formed of synthetic material which generally has a relatively lower tensile strength than the nylon heretofore used, which stretches less readily, and which undergoes a smaller maximum elongation prior to break. As a result, the elongation characteristics of the web of this invention are more closely matched to those of the paper layers 100. This results in a greater proportion of the tensile load being absorbed by the reinforcing web, and a smaller proportion by the weaker paper layers 100. The surprising outcome is that, even though the maximum tensile strength of the reinforcing web 106 alone is lower than that of a prior art reinforcing web alone, the maximum tensile stress to which the composite fabric 124 can be subjected before paper rupture occurs is significantly greater than that for the prior art composite wherein nylon of the foregoing type has been used as the reinforcing web, thus providing a superior end product.

Preferably, the paper-like layers 100 have an upper elongation range limit of at least about 25% and the reinforcing netting 106 has a lower elongation range limit of at most about 20% A preferred class of materials for the reinforcing web 106 are polyolefins, polypropylene being particularly preferred. Other polyolefins such as, e.g., polyethylene can also be used, as can a variety of other polymeric thermoplastic materials which the art is able to manufacture with the proper elongation characteristics to match those of the paper layers 100.

A particular material which has been used with success is Conwed oriented plastic netting, which is available in a satisfactory range of elongation characteristics, filament sizes, etc., from the Plastic Division of the Conwed Corporation, Minneapolis, Minn. This material is a biaxially oriented, open mesh polypropylene net which is sold by the above mentioned supplier at prices which represent a considerable saving relative to prior art reinforcing web materials. Thus, not only is the absolute tensile strength of the composite material 124 improved over the prior art, but its cost is simultaneously reduced, and its cost effectiveness, in terms of tensile strength per unit cost, is therefore significantly improved.

An additional advantage of the preferred reinforcing web material is that it is manufactured by a particular process which leaves it substantially free of residual internal stresses and distortions. In the past, the mesh used for the reinforcing web of disposable fabrics was formed from nylon filaments by a process in which the filaments are first extruded and then cross-laid over one another and adhesively bonded to each other at their intersections. Descriptions of this cross-laying process are seen in US. Pats. Nos. 2,900,980 and 3,072,511 of K. I. Harwood. The result is a net material with substantial residual stresses and distortions owing to the pull exerted between the strands thereof. This has been found to cause uneven stretching and distortion of the disposable fabric end product. The latter characteristic in turn causes difficulty in rolling, unrolling, laying, cutting, sewing and otherwise handling the fabric, and also distorts its hanging or draping characteristics when incorporated into a fashionable feminine garment.

In contrast, the preferred reinforcing web material 106 is integrally extruded, a term which is used herein to refer to a process for the extrusion of netting material in which the filaments of the netting are already in place in the network at the time that they are extruded. In other words, instead of first extruding linear filaments and then cross-laying them to form a network, the net emerges directly from the extruder in network form, and the strands thereof are integral with each other at the network intersections. The Conwed material mentioned above is of this type, and the process of integrally extruding such material is described in US. Pats. Nos. 3,051,987 and 2,919,467 of F. B. Mercer, and US. Pat, No. 3,252,181 of J. Hureau. The advantage of the integral extrusion process is that the net material 106, as it emerges fully formed from the extruder, has no residual stresses or distortions. Moreover, no cross-laying process need be employed thereafter to form the network and incidentally to produce stresses and distortions.

As a result, the preferred reinforcing web material 106 results in a disposable fabric product 124 which has no uneven stress or distortion characteristics, and consequently causes no difficulties in rolling, unrolling, laying, cutting, sewing, or otherwise handling the fabric. In addition it does not adversely affect the hang or drape of the material if it should be used in fashionable womens gaments.

It will now be appreciated that this invention provides an improved disposable fabric material which employs a reinforcing web material of different characteristics to achieve a composite fabric which retains its utility up to higher tensile load levels, which is more economical, both absolutely and in terms of strength per unit cost, and which in addition has superior characteristics for handling and incorporation into garments and a variety of other end products.

The invention claimed is:

1. A disposable laminar fabric comprising paper bonded to a polyolefin reinforcing netting, wherein the lower limit of the reinforcing netting maximum percent elongation range is at most about 20% and the upper limit of the paper maximum percent elongation range is at least about 25%.

2. A fabric as in claim 1 wherein said polyolefin is polypropylene.

3. A fabric as in claim 1 wherein said netting is disposed between two sheets of paper.

References Cited UNITED STATES PATENTS 3,448,000 6/1969 Paquin et a1. 16l250 3,194,872 7/1965 Garner 16l-250X 2,919,467 1/1960 Mercer 264103 OTHER REFERENCES Chemical Engineering, Mar. 11, 1968, pp. 104-105.

PHILIP DI-ER, Primary Examiner US Cl. X.R. 164-79, 85, 109, 113, 166, 250; 249; 156309 

